System and method for stimulating multiple production zones in a wellbore with a tubing deployed ball seat

Abstract

A system and method for selectively stimulating a plurality of producing zones in a wellbore in oil and gas wells. The system includes a plurality of modules connected in a string that may be selectively actuated to stimulate a producing zone. Each module may be adapted to engage a tubing run ball seat. After installation of the string within the wellbore, a ball seat may be run into the well and positioned to selectively engage a desired module. The ball seat may be used to open a sleeve of the module permitting the stimulation of the producing zone. After stimulation of the producing zone, the ball seat may be removed from the wellbore rather than needing to drill out the ball seat. The sleeve may include a profile adapted to engage a shifting tool permitting the selective closure of the sleeve after stimulation of the producing zone.

What is claimed is: 
     
       1. An apparatus for selectively stimulating a formation within in a wellbore, the apparatus comprising:
 a housing connected to a fracturing string, the housing having a fracture port permitting fluid communication between an inner bore of the housing and an exterior of the housing, the housing including a fracture sleeve that is movable between an open position and a closed position, wherein the closed position prevents fluid communication between the inner bore and the exterior of the housing; and 
 a ball seat assembly that is adapted to selectively engage the housing, the ball seat assembly comprising: 
 a ball seat adapted to sealingly engage a ball having a predetermined diameter; 
 a key connected to the ball seat, the key being adapted to selectively mate with a profile on the fracture sleeve; 
 a lock sleeve connected to the ball seat, the lock sleeve being movable from an initial unlocked position to a locked position, the lock sleeve being biased to the locked position, in the locked position the lock sleeve being adapted to selectively retain the key in a mated position with the profile on the fracture sleeve. 
 
     
     
       2. The apparatus of  claim 1 , wherein the ball seat assembly is adapted to be installed onto a housing of a fracturing string already positioned within a wellbore. 
     
     
       3. The apparatus of  claim 1  further comprising a spring, wherein the spring biases the lock sleeve to the locked position. 
     
     
       4. The apparatus of  claim 1  further comprising a collet finger, the collet finger adapted to selectively engage a first recess in the housing when the fracture sleeve is in the closed position and engage a second recess in the housing when the fracture sleeve is in the open position. 
     
     
       5. The apparatus of  claim 1  further comprising a shearable device that selectively retains the fracture sleeve in the closed position, the shearable device adapted to shear and release the fracture sleeve upon the application of a predetermined pressure differential. 
     
     
       6. The apparatus of  claim 1  further comprising a leaf spring connected to the ball seat, the leaf spring adapted to move the key to an expanded position, wherein the key is in the expanded position when engaged with the profile on the fracture sleeve. 
     
     
       7. The apparatus of  claim 1 , wherein the lock sleeve includes an exterior profile adapted to engage a profile on a running tool. 
     
     
       8. The apparatus of  claim 7 , wherein the exterior profile of the lock sleeve is adapted to engage a lock dog on the running tool. 
     
     
       9. The apparatus of  claim 7 , wherein the exterior profile of the lock sleeve is adapted to engage a profile on a retrieval tool. 
     
     
       10. The apparatus of  claim 9 , wherein the running tool is adapted to position the ball seat assembly into a wellbore to selectively engage the housing of the fracture string when the fracture sleeve is in the closed position. 
     
     
       11. The apparatus of  claim 10 , wherein the retrieval tool is adapted to release the ball seat assembly from the housing of the fracture string when the fracture sleeve is in the open position. 
     
     
       12. A method of selectively fracturing multiple zones within a wellbore with a single trip into the wellbore with a fracture string, the method comprising:
 running at least a first ball seat assembly into a wellbore; 
 selectively connecting the first ball seat assembly onto a first housing on the fracture string within the wellbore, wherein the fracture string is positioned in the wellbore prior to running the first ball seat assembly into the wellbore; 
 running at least a second ball seat assembly into the wellbore after running the first ball seat assembly; 
 selectively connecting the second ball seat assembly to a second housing on the fracture string; 
 applying pressure to the fracturing string to open a hydro port sub on the fracture string; 
 inserting a first ball in the fracture string, the first ball adapted to seat on the first ball seat and prevent fluid flow within the fracture string past the first ball seat; 
 pumping fluid down the fracture string to create a pressure differential, the pressure differential moving a sleeve within the first housing opening a first fracture port; 
 fracturing a formation adjacent the first fracture port; 
 inserting a second ball in the fracture string, the second ball adapted to seat on the second ball seat and prevent fluid flow within the fracture string past the second ball seat; 
 pumping fluid down the fracture string to create a pressure differential, the pressure differential moving a sleeve within the second housing opening a second fracture port; and 
 fracturing a formation adjacent to the second fracture port. 
 
     
     
       13. The method of  claim 12  further comprising running a third ball seat assembly into the wellbore and selectively connecting the third ball seat assembly onto a third housing on the fracture string within the wellbore, wherein the third ball seat assembly is run into the wellbore after fracture the formation adjacent to the second fracture port. 
     
     
       14. The method of  claim 13  further comprising inserting a third ball in the fracture string, the third ball adapted to seat on the third ball seat and prevent fluid flow within the fracture string past the third ball seat, wherein the third ball has a diameter that is same as a diameter of the first ball. 
     
     
       15. The method of  claim 14  further comprising pumping fluid down the fracture string to create a pressure differential, the pressure differential moving a sleeve within the third housing opening a third fracture port and fracturing a formation adjacent to the third fracture port. 
     
     
       16. The method of  claim 15  further comprising removing the first ball seat assembly, the second ball seat assembly, and the third ball seat assembly from the wellbore. 
     
     
       17. The method of  claim 16  further comprising moving at least one of the sleeves to close one of the fracture ports. 
     
     
       18. The method of  claim 12 , wherein the first ball seat assembly is run into the wellbore selectively connected to a running tool. 
     
     
       19. The method of  claim 18 , wherein selectively connecting the first ball seat assembly onto the first housing comprises moving the running tool downhole past the first housing and pulling the running tool uphole past the first housing engaging a first profile on the first ball seat assembly with a profile on the sleeve of the housing to selectively retain the first ball seat assembly to the sleeve of the housing. 
     
     
       20. A method for completing a hydrocarbon producing wellhole, comprising:
 running a ball seat assembly on a running tool into a work string within a wellbore, wherein the work string is positioned in the wellbore prior to running the ball seat assembly into the work string; 
 selectively connecting the ball seat assembly to a portion of the work string, the portion having a port and a sleeve movable between a closed position preventing fluid communication through the port and an open position allowing fluid communication through the port; 
 inserting a first ball into the work string, the first ball adapted to seat on the ball seat assembly preventing fluid flow through the work string past the ball seat; 
 applying a pressure differential within the work string, wherein upon the application of a predetermined pressure differential the sleeve moves to the open position; and 
 treating a well formation through the open port. 
 
     
     
       21. The method of  claim 20  further comprising releasing the ball seat assembly from the portion of the work string and retrieving the ball seat assembly from the work string. 
     
     
       22. The method of  claim 21 , wherein a retrieving tool releases and retrieves the ball seat assembly. 
     
     
       23. The method of  claim 21  further comprising moving the sleeve to a closed position. 
     
     
       24. The method of  claim 23 , wherein a shifting tool is used to move the sleeve to the closed position. 
     
     
       25. The method of  claim 20  further comprising running a second ball seat assembly into the work string and selectively connecting the second ball seat assembly to a second portion of the work string, the second portion having a second port and a second sleeve movable between a closed position preventing fluid communication through the second port and an open position allowing fluid communication through the second port. 
     
     
       26. The method of  claim 25  further comprising inserting a second ball into the work string, the second ball adapted to seat on the second ball seat assembly preventing fluid flow through the work string past the second ball seat, applying a pressure differential within the work string to move the second sleeve to the open position, and treating a well formation through the open second port. 
     
     
       27. The method of  claim 26 , wherein the first ball and the second ball are the same size. 
     
     
       28. A system for treating multiple zones of a wellbore with a single trip of a work string, the system comprising:
 a work string positioned within the wellbore; 
 a first plurality of housings located along the work string, each housing of the first plurality of housings having a port and a sleeve movable to open and close the port; 
 a second plurality of housings located along the work string, each housing of the second plurality of housings having a port and a sleeve movable to open and close the port; 
 a first plurality of ball seat assemblies adapted to be run into the work string already positioned in the wellbore, each of the first plurality of ball seat assemblies adapted to selectively mate with a housing of the first plurality of housing; 
 a first plurality of balls each being a different size adapted to be inserted individually into the work string, each ball of the first plurality of balls adapted to be retained by a corresponding ball seat assembly within the first plurality of ball seat assemblies, wherein an application of a pressure differential to the work string moves the sleeve and opens the port of each housing of the first plurality of housings; 
 a second plurality of ball seat assemblies adapted to be run into the work string already positioned in the wellbore, each of the second plurality of ball seat assemblies adapted to selectively mate with a housing of the second plurality of housings; and 
 a second plurality of balls each being a different size adapted to be inserted individually into the work string, each ball of the second plurality of balls adapted to be retained by a corresponding ball seat assembly within the second plurality of ball seat assemblies, wherein an application of a pressure differential to the work string moves the sleeve and opens the port of each housing of the second plurality of housings. 
 
     
     
       29. The system of  claim 28 , wherein the different sizes of the first plurality of balls is identical to the different sizes of the second plurality of balls. 
     
     
       30. The system of  claim 28  further comprising a third plurality of housings located along the work string each having a port and a sleeve movable to open and close the port, a third plurality of ball seat assemblies adapted to be run into the work string already positioned in the wellbore each adapted to selectively mate with a housing of the third plurality of housing, and a third plurality of balls each being a different size adapted to be inserted individually into the work string, each ball adapted to be retained by a corresponding ball seat assembly within the third plurality of ball seat assemblies, wherein an application of a pressure differential to the work string moves the sleeve and opens the port of each housing of the third plurality of housings. 
     
     
       31. The system of  claim 30 , wherein the different sizes of the first plurality of balls is identical to the different sizes of the third plurality of balls.